1. Field of the Invention
This invention relates to disk drive suspensions and, more particularly, to load beams for disk drive suspensions. The invention suspensions utilize microactuation by a piezoelectric crystal to shift the load beam distal end relative to a disk to be read.
2. Related Art
Load beams are used to carry sliders containing read/write heads adjacent spinning disks. The load beam has a base portion anchored to an actuator arm that pivotally shifts the load beam and its associated slider angularly to move between tracks on the disk. The mass and inertia of conventional actuators means it requires considerable power to operate them.
It is an object of the present invention to provide an improved suspension. It is a further object to provide a load beam of novel design. It is a further object to provide for the actuation of a suspension load beam with microactuators acting against a bendable beam spring portion having an expansion and contraction capability. It is a further object to utilize piezoelectric crystals acting between the load beam base portion and the beam portion across the spring portion under voltages of less than about 40 volts and achieving displacements of the load beam carried slider of about 2 micrometers in the Y-axis. It is a still further object to provide a load beam having specially conformed spring elements to support the beam portion but also to readily allow changes in dimension of the spring portion through the decrease or increase in an arcuate section of the spring elements. Yet another object is to selectively reduce, as by etching, the initial or given thickness of the spring elements to facilitate bending action.
The invention accordingly provides a disk drive suspension comprising a load beam having a base portion, a spring portion and a beam portion adapted to carry a slider in operating proximity to a disk, a dimensionally variable electrodynamic microactuator coupled to the base portion and the beam portion and across the spring portion in beam portion displacing relation to the base portion over a distance that is a function of an applied voltage to the microactuator and the resistance of the spring portion to changes in dimension, the spring portion being locally bendable to provide low resistance change in spring portion dimensions, whereby the beam portion is displaced an increased distance at a given applied voltage.
In this and like embodiments, typically, the suspension includes left and right hand microactuators acting from the base portion on the beam portion in displacing relation, the microactuator is angled relative to the longitudinal axis of the load beam in a manner to apply a torque force on the spring portion, the microactuator comprises a piezoelectric crystal, and/or the applied voltage is less than about 40 volts, the beam portion is displaced up to 2 micrometers in the Y-axis, and the spring portion is locally reduced in thickness relative to said beam portion thickness for reduced resistance to bending.
In a further embodiment the invention provides a disk drive suspension comprising a load beam having a base portion, a spring portion and a beam portion adapted to carry a slider in operating proximity to a disk, a left and right hand, dimensionally variable, piezoelectric crystal microactuator each coupled to the base portion and the beam portion and across the spring portion in beam portion displacing relation to the base portion over a distance that is a function of an applied voltage to the microactuator and the resistance of the spring portion to changes in dimension, the spring portion comprising a locally arcuate spring elements providing low resistance change in spring portion dimensions, whereby the beam portion is displaced an increased distance at a given applied voltage.
In this and like embodiments, typically, the spring portion comprises left and right spring elements, each spring element having an arcuate section, the arcuate sections tending to flatten to a greater radius curve when the spring portion element is elongated by action of the microactuator and to curl to a lesser radius curve when the spring portion element is contracted by action of the microactuator and individually for each spring element, the left and right hand microactuators are angled to converge toward each other, e.g. at an included angle of between 5 and 60 degrees, at the proximate end of the load beam toward the longitudinal axis of the load beam in a manner to each apply a separate torque force on the spring portion, each spring element has an arcuate section intermediate the spring element ends, the arcuate sections tending to flatten to a greater radius curve when the spring portion element is elongated by action of the microactuator and to curl to a lesser radius curve when the spring portion element is contracted by action of the microactuator and individually for each spring element, each spring element comprises a unitary part of a common web with the beam base portion and the beam portion, the spring element having fore and aft tabs connected to the beam and base portions respectively and an arcuate section connected to the fore and aft tabs in beam supporting relation relative to the base, the spring elements being generally parallel, separated and of like curvature in their arcuate sections, the spring portion comprises left and right spring elements, the spring element arcuate sections being etched over the central portion thereof, e.g. over the middle 20 to 40% of the section length, to a reduced thickness relative to the remainder of the arcuate sections, and the microactuator right and left piezoelectric crystals are coupled between the base and beam portions inboard of the left and right spring elements, and/or each piezoelectric crystal is about 0.0075 inch in thickness, the applied voltage is less than 40 volts, the beam portion is displaced up to 2 micrometers in the Y-axis,
In its method aspects, the invention provides the method of actuating the beam portion of a load beam having a base portion, a spring portion and a beam portion, including shifting the left and/or right hand side of the beam portion responsive to a torque forces exerted by a microactuator between the base portion and the beam portion, and supporting the beam portion with a load beam spring portion comprising left an right hand bendable spring elements, the method further typically including defining an arcuate portion in each spring element that increases or decreases in radius in response to exertion of torque forces to facilitate greater distance beam displacement at lower levels of voltage, and optionally defining an etched zone of reduced thickness intermediate the ends of said spring element arcuate portion.